#386 - Aging clocks—what they measure, how they work, and their clinical and real-world relevance
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In this deep-dive episode of The Peter Attia Drive, Peter Attia explores the science, utility, and limitations of aging clocks—biological markers designed to estimate biological age and the pace of aging. He begins by distinguishing chronological age from biological age and the pace of aging, explaining how epigenetic clocks, particularly those based on DNA methylation at CpG sites, attempt to compress complex aging processes into single predictive numbers. Attia examines two pivotal studies: the DO-HEALTH trial, which tested omega-3, vitamin D, and exercise in older adults and found that only omega-3 supplementation consistently shifted three of four aging clocks (PhenoAge, GrimAge2, DunedinPACE), though the effect was small (about three months of reduced aging over three years); and the Dunedin PAC-NI study, which developed a brain MRI-based clock that predicts aging rate using structural brain features and showed strong associations with future dementia, frailty, and mortality—even in people who were still healthy at age 50. Despite the promise of these tools for accelerating aging research, Attia emphasizes that no current clock has been proven to reliably predict meaningful clinical outcomes like lifespan or disease risk at the individual level.
Aging clocks compress complex biological aging into single numbers but vary significantly in what they measure and how they perform.
Omega-3 supplementation showed consistent, though small, effects on multiple epigenetic clocks in a large trial, while vitamin D and exercise did not.
The Dunedin PAC-NI brain MRI-based clock successfully predicted future health outcomes like dementia and mortality using only a single scan from midlife.
Despite statistical associations, the clinical utility of aging clocks remains uncertain—changing a clock score doesn’t yet prove it changes real-world health outcomes.
At the individual level, traditional biomarkers (blood pressure, glucose, lipids, fitness) remain more reliable and actionable than biological age scores.
Introduction to Aging Clocks and Their Promise
Peter Attia introduces the concept of aging clocks as potential proxies for biological aging, explaining their role in accelerating research by offering faster, measurable outcomes than traditional clinical endpoints like mortality or disease incidence.
Understanding Epigenetic Clocks and DNA Methylation
Attia breaks down the science behind epigenetic clocks, focusing on DNA methylation at CpG sites, how these changes correlate with aging, and why they serve as a molecular record of biological wear and tear.
The Evolution from Chronological to Biological Age
The episode explores how aging clocks evolved from simply predicting chronological age to estimating biological age and pace of aging, with a focus on next-generation models like PhenoAge, GrimAge, and DunedinPACE.
The DO-HEALTH Trial: Testing Interventions on Aging Clocks
“The only clock that it didn't move the needle in was the first gen GrimAge clock. Now, that said, even though the omega-3 change showed consistency in three of the four tests, the magnitude of the effect was quite small. So if you translate it into something a little more intuitive, the effect corresponded to about three months of reduced aging over three years.”
The Dunedin PAC-NI Brain MRI Clock: Predicting Aging from the Brain
“The real test for the rubber hitting the road on this is how will this clock work in people who are older, which are therefore outside of your calibration window? And to do that... they went to look at two cohorts... and in both, faster aging according to the model was associated with more rapid hippocampal atrophy... and a roughly 30% higher risk of death during follow-up.”
“At least for me, I think about this as if someone were to offer a biological age score, it's worth asking them what that number is actually telling them. Is it telling them something new? Or at best, is it just repackaging information you already have or understand?”
“All models are wrong, some are useful. But the question is how useful are these models?”
“The real test for the rubber hitting the road on this is how will this clock work in people who are older, which are therefore outside of your calibration window?”
Host
Peter Atiyah
person
DO-HEALTH study
other
Dunedin Multidisciplinary Health and Development Study
other
Dunedin PAC-NI
other
PhenoAge
other
GrimAge
other
Dunedin Pace
other
GrimAge2
other
UK Biobank
other
Alzheimer's Disease Neuroimaging Initiative
other
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